The present invention relates generally to a system and methods for inducing cardioplegic arrest and for performing cardiopulmonary bypass procedures. More particularly, the invention relates to an aortic catheter having a porous aortic root balloon for controlling flow through the coronary arteries and the aortic lumen, and for inducing cardiac arrest. The invention further relates to devices for maintaining the competence of a patient""s aortic valve and for preventing unwanted flow through the aortic valve.
Recent advances in the field of minimally invasive cardiac surgery have included the development of aortic catheters and methods for inducing cardiac arrest without the necessity of opening the patient""s chest with a sternotomy or other major thoracotomy. For example, U.S. Pat. No. RE 35,352 to Peters describes a single balloon catheter for occluding a patient""s ascending aorta and a method for inducing cardioplegic arrest. A perfusion lumen or contralateral arterial cannula is provided for supplying oxygenated blood during cardiopulmonary bypass. U.S. Pat. No. 5,584,803 to Stevens et al. describes a single balloon catheter for inducing cardioplegic arrest and a system for providing cardiopulmonary support during closed chest cardiac surgery. A coaxial arterial cannula is provided for supplying oxygenated blood during cardiopulmonary bypass. The occlusion balloon of these catheters must be very carefully placed in the ascending aorta between the coronary arteries and the brachiocephalic artery, therefore the position of the catheter must be continuously monitored to avoid complications.
In clinical use, in patients with incompetent or regurgitant aortic valves, antegrade infusion of cardioplegia by aortic root injection is contraindicated because the pressure generated by infusion of cardioplegia overcomes the reduced competence of the valve, causing cardioplegia to enter the ventricle rather than entering the coronary arteries. In some cases the left ventricle may become distended. In patients with incompetent or regurgitant aortic valves, it is recommended that cardioplegia be administered by direct coronary cannulation or by retrograde perfusion through the coronary sinus. Direct coronary cannulation can be difficult and can dislodge plaques from ostial lesions in the coronary arteries. Retrograde perfusion of cardioplegia through the venous system has been used successfully, however, there is debate as to the effectiveness of this procedure, and correct placement of the catheters can be difficult. Furthermore, even in patients with normal aortic valves, pressures generated during surgery may cause the valve to become temporarily incompetent, leading to problems similar to those discussed above.
Another difficulty encountered with prior art aortic catheters is the tendency of the single balloon catheters to migrate or drift in the direction of the pressure gradient within the aorta. Specifically, during infusion of cardioplegia, the balloon catheter will tend to drift downstream away from the heart and toward the aortic arch and, while the cardiopulmonary bypass pump is on during the procedure and after completion of infusion of cardioplegia, the balloon catheter will tend to drift upstream in the opposite direction toward the heart into the aortic root. This migration can be problematic if the balloon drifts downstream far enough to occlude the brachiocephalic artery, or upstream enough to occlude the coronary arteries, or to pass through the aortic valve into the ventricle.
What is needed is a peripheral or central access catheter configuration that maintains the competence of weakened aortic valves, and does not challenge the competence of healthy aortic valves, during infusion of cardioplegia, and is more resistant than prior apparatus to migration due to pressure gradients within the patient""s aorta.
The following patents are hereby incorporated herein in their entirety: U.S. Pat. Nos. 5,383,854, 5,308,320, 5,820,593, 5,879,316, 5,906,588 and 6,165,162 by Safar et al.; filed Sep. 11, 1998, by Safar et al.; U.S. Pat. No. 5,738,649 by John A. Macoviak; U.S. Pat. Nos. 5,827,237, 5,833,671 and 6,059,757 by John A. Macoviak and Michael Ross; and U.S. Pat. No. 6,117,105, by Bresnahan et al.
Accordingly, the present invention provides an aortic catheter or cannula having a distal flow control member located at or near a distal end of the cannula. The distal flow control member is positioned within the aortic root and is intended to fulfill at least one and preferably all five of the following functions: occluding the aorta at the aortic root, perfusing the coronary arteries with a selected fluid, maintaining the competence of the aortic valve when perfusing the coronary arteries, resisting migration of the distal flow control member or cannula, and providing a bumper for tactile feedback when placing the catheter. Preferably, the distal flow control member may be an inflatable balloon that is inflated using a cardioplegia fluid, and which will occlude the aorta and deliver an effective volume of cardioplegia fluid to the coronary arteries. The distal flow control member may be shaped to conform to the shape of the aortic root and may also be shaped to conform to the cusps of the aortic valve. The material or materials used in the inflatable distal flow control member should have properties that allow an internal pressure within the distal flow control member to be maintained at a sufficient level to occlude the aorta, while also allowing a controlled volume of fluid to seep or otherwise escape from the balloon for perfusing the coronary arteries. Thus, the surface of the balloon may be porous, or have one or more porous regions, or include apertures that allow cardioplegia to seep or flow when a specific pressure is attained, and/or to prevent flow of cardioplegia when the pressure is higher or lower than ideal for coronary perfusion.
The catheter may further include one or more additional flow control members located downstream from the distal flow control member to segment the aorta for selective perfusion to different organ systems within the body. These flow control members may be inflatable balloons or selectively deployable external catheter valves. The catheter may further include one or more anchoring members located downstream from the distal flow control member. The downstream anchoring member may be a larger inflatable balloon or other anchoring structure that provides sufficient force or friction to prevent the catheter from drifting from a selected position within the aorta. Useable flow control members include, but are not limited to, expandable or inflatable members such as inflatable balloons and valves including collapsible/expandable valves of various configurations including retrograde valves, antegrade valves, and various central flow and peripheral flow valves.
A combination of valves and inflatable members may be used as appropriate for a given procedure, thus in some embodiments, the catheter body can include one or more antegrade and retrograde valves, as well as one or more inflatable balloons. Inflatable balloons and collapsible/deployable valves suitable for this application have been previously described in the patents incorporated by reference above and any desirable or practical inflatable balloon or deployable valve may be used. Inflatable balloons typically include an interior chamber that is in fluid communication with an inflation lumen extending within the catheter shaft a location from within the respective flow control member to a location in the proximal portion which is adapted to extend out of the patient.
A first embodiment of the aortic catheter system of the present invention is configured for retrograde deployment via a peripheral artery, such as the femoral artery. The aortic catheter has an elongated catheter shaft having a proximal end and a distal end. A distal flow control member, preferably in the form of an inflatable balloon, is mounted on the catheter shaft near the distal end of the catheter shaft so that it may be positioned within the aortic root when deployed. An inflation and cardioplegia lumen extends through the catheter shaft to one or more inflation ports within the distal flow control member. In the preferred embodiment, a guide wire lumen extends from the proximal end of the catheter shaft to the distal end of the shaft, and may have a hydrophilic or lubricious coating. Generally, the distal flow control member comprises an impermeable portion and a permeable portion. More exemplary embodiments will now be discussed.
In a second embodiment, the distal flow control member is a three-lobed balloon to conform to the shape of the aortic valve. In a third embodiment the distal flow control member is comprised of a balloon formed of a non-porous material, but having two or more porous windows that align with the coronary ostia for delivery of cardioplegia. In a fourth embodiment, the distal flow control member comprises a balloon comprising both a non-porous material portion, and a porous portion that extends circumferentially around the diameter of the balloon. In a fifth embodiment, bistable nipples or pressure valves are used. In a sixth embodiment, the distal flow control member comprises three adjacent balloons on the catheter shaft, with the most distal balloon conforming to the shape of the aortic valve, the middle balloon being porous, and the most proximal balloon being non-porous. In a seventh embodiment, a second balloon is positioned within a first outer balloon. When the inner balloon is fully inflated, the outer surface of the inner balloon contacts the inner surface of the outer balloon preventing escape of cardioplegia through the porous portions, nipples, or pressure valves located on the outer balloon. When the inner balloon is deflated, cardioplegia is allowed to flow. In an eighth embodiment, the distal flow control member comprises two adjacent balloons on the catheter shaft having porous surfaces facing each other.
In each embodiment discussed above, the distal flow control member preferably resists migration because the distal flow control member comprises a diameter larger than the diameter of the sinotubular ridge and the aortic valve annulus. In alternate embodiments, the surface of the flow control member may include a sticky polymer coating to further resist migration.
In a ninth embodiment of the invention, describes a catheter system for retrograde deployment that includes an additional occluding/anchoring member is described. In this configuration, the aortic catheter has an elongated catheter shaft having a proximal end and a distal end. Any of the previously described porous root balloons may be implemented. The porous aortic root balloon is mounted on the catheter shaft near the distal end of the catheter shaft so that it may be positioned within the aortic root when deployed and is capable of occlusion and cardioplegia delivery. An occluding/anchoring member, hereafter referred to as the anchoring member, in the form of an inflatable balloon, is mounted on the catheter shaft proximal to the porous root balloon and at a position located in the descending aorta when deployed. Preferably, an arch perfusion lumen extends through the catheter shaft from the proximal end to one or more arch perfusion ports on the exterior of the catheter shaft between the porous root balloon and the downstream anchoring member, to perfuse the aortic arch. An arch pressure lumen preferably extends through the catheter shaft from the proximal end to an arch pressure port located between the distal flow control member and the anchoring member to monitor pressure in the aortic arch. At least one inflation lumen extends through the catheter shaft from the proximal end to one or more balloon inflation ports located on the catheter shaft within the distal flow control member and the anchoring member. In other embodiments, each flow control member may be deployed using a separate lumen. A guide wire lumen extends from the proximal end of the catheter shaft to the distal end of the shaft. The distal flow control member used in this embodiment would be similar to the distal flow control member and alternative embodiments described previously. Occlusion of the aorta by the anchoring balloon may also be used to partition the aorta for differential perfusion of the partitioned portions.
In a tenth embodiment, otherwise similar to the ninth embodiment described above, the system performs the partitioning function of the anchoring balloon with a valve, which enables the partitioning of the aorta for differential perfusion.
Furthermore, methods according to the invention are described using the aortic catheter for occluding the ascending aorta at the aortic root and for perfusing a selected fluid to the coronary arteries and/or inducing cardioplegic arrest, for supporting the patient""s circulation on cardiopulmonary bypass, for partitioning the patient""s aorta and for performing selective aortic perfusion.